Wave guide-to-coaxial line coupling for traveling wave amplifiers



Apnl 11, 1961 M. MAGID 2,979,636

WAVE GUIDE-TO-COAXIAL LINE COUPLING FOR TRAVELING WAVE AMPLIFIERS Filed Jan. 5, 1959 "i. TI' a VfS Q 1*? L I mm m u, N "5 K Y IN V EN TOR.

MAX MA 670 tfl See Pa WAVE GUIDE-TO-COAXIAL LINE COUPLING FOR TRAVELING WAVE AMPLIFIERS Max Magid, Passaic, NJ., assignor to the United States of America as represented by the Secretary of the Air Force Filed Jan. 5, 1959, Ser. No. 785,101

2 Claims. (Cl. 31539.3)

This invention relates to high frequency electrical transmission and particularly to the coupling of transmission components of different characters, as for example, the coupling of a hollow wave guide to the helix delay line of a traveling wave amplifying tube type of coaxial transmission line.

An object of the invention is to provide wave guideto-coaxial line coupling means of low-loss characteristics and including features having advantages of high utility when incorporated into a coaxial line in the form of a traveling wave type of amplifier.

More specifically, the invention includes a wave guide having a tapering ridge of ramp-like contour, coacting with a shorting plunger to minimize losses and facilitate precise impedance matching at the point of coupling of the wave guide power to the coaxial cavity; the latter being disposed within the range of the focusing solenoid surrounding the helix delay line, and in direct apposition to the input end of the helix, to achieve maximum coupling efilciency.

An additional feature resides in the provision of a hollow metallic tube to telescopically receive the traveling wave tube and to serve as the inner conductor of the coaxial line. This feature further enhances the efliciency of the coupling action, as between the coaxial cavity and the helix delay line within the tube.

These and other features, objects, and characteristics of the invention will be better understood upon reference to the following description of the embodiment of the invention illustrated in the accompanying drawings wherein:

Fig. 1 is a longitudinal sectional view showing the wave guide and coaxial line components in assembled and operating relationship;

Fig. 2 is a view along line 2-2 of Fig. l; and

Fig. 3 is a view of part of the Fig. 1 assembly, but on a larger scale.

As shown best in Fig. 1, the assembly includes a rectangular hollow wave guide attached to the coaxial line assembly by the fusion of one wall of the wave guide to a circular flange 11 provided on the inner end of metallic tube 12 serving as the outer conductor of the coaxial line; said tube 12 also serving as the tubular support for dielectric spool 13 on which the multiple turns of conductor wire (or foil) are wound, to form solenoid 14. Outer conductor 12 is electrically grounded by reason of its physical integration, at its outer end portion, with shank 16 of end cap 17, the latter being threaded into the metallic housing 18, grounded as indicated at 19. Flanges 21 and 22 on dielectric spool 13 complete the insulation of solenoid 14 from the other parts above referred to.

The inner conductor of the coaxial line is constituted by metallic tube 26, concentric with outer conductor 12 ice 2" to form the annular, coaxial cavity resonator 24. Inner conductor 26 extends transversely through tapering ramplike ridge 15 of wave guide 10, where it is held in place by the shank 27 of dielectric bushing 28, the latter being secured to the out-board wall of the wave guide by suitable means 29.

The traveling wave amplifier tube components are mounted along the common axis of conductors 12 and 26, and include the usual helix delay line 31 and its supporting quartz tubing 32, the latter being fused to the electron gun capsule 33, at its inner end, and piloted in dielectric bushing 34 at its outer end. The pins of capsule 33 are engageable by the adapter base 35 whose outwardly projecting pins constitute the usual means for applying voltages to the gun elements within capsule 33.

Annular collar 41, slidable along helix tube 32 to the desired position, serves to define the outer axial limits of resonant cavity 24, whose inner limits are defined by the relatively narrow annular space 25 adjacent the annular iris 20 in the wave guide wall, at the region where conductor 26 passes into said wave guide, for coupling the wave guide output to the coaxial cavity resonator.

The coupling action just referred to occurs with minimum power loss, due largely to the fact that the described concentric nesting of the traveling wave tube capsule 33 within the inner conductor 26, of the coaxial line, serves to position the helix delay line 31 in eflective, intimate coupling relationship to cavity 24, so that the high frequency field is of maximum efliciency in producing energy input, with optimum noise control, to the helix 31. Moreover, this effective coupling of the generated energy is brought about without the necessity of resorting to a splitting of the solenoid structure, as in prior art couplers.

The wave guide ramp construction indicated at 15 facilitates matching of the wave guide impedance to the relatively low impedance of the coaxial line. The preciseness of the matching operation is further controllable by adjusting the position of shorting plunger 40, which serves to close off, to the degree desired, the upper area (as shown) of the free space between ramp 15 and iris 20.

What I claim is:

1. In combination with a wave amplifying device having a helix delay line axially disposed therein, and also having a cavity resonator adjacent one end of said helix delay line, a coaxial line including a metallic tube defining the peripheral limits of said cavity resonator, means mounted within said metallic tube for delivering electron flow-producing current to said wave amplifying device, and wave-guiding means surrounding said metallic tube for supplying impedance matching wave energy to said cavity resonator, said wave guiding means including a ramp-like structure positioned adjacent the input end of said cavity resonator, with the outlet end of the wave guiding means having communication with said cavity resonator by way of the annular space encompassed by said coaxial line.

2. In combination with a wave amplifying device having a helix delay line axially disposed therein, and also having a cavity resonator adjacent one end of said helix delay line, a coaxial line including a metallic tube defining the peripheral limits of said cavity resonator, means mounted within said metallic tube for delivering electron flow-producing current to said wave amplifying device, and wave-guiding means surrounding said metal lic tube for supplying impedance matching wave energy to said cavity resonator, said wave-guiding means includ ing a ramplike structure integrated with one end of said wave almplifying device, said ramp-like structure having References Cited in the filepf thlspatcntv,

its out et end in communication with said cavity re'sc i I nator by way of the annular space encompassed by said UNITED STATES PATENTS coaxial line, and complementary means arched around 2,416,565 Beggs Feb. 25, 1947 approximately one-half the periphery of said inner con- 5 2,445,992 Beggs July 27, 1948 centric metallic tube, and ,grovable in relation to said 2,672,571 Harmon Mar. 16, 1954 ramp-like structure, for adjusting said impedance char- 2,812,470 Cook -i Nov. 5, 1957 acteristics.- 2,836,758 Chodorow May 27, 1958 

